We live in an age of intolerant individualism. Anything goes — until suddenly it doesn’t. In the anarchy of identity politics, the absence of rules makes everyone feel insecure. And insecurity breeds intolerance, with all its attendant vices: safe spaces, virtue-signalling, no-platforming. The culture of intolerant individualism preaches diversity but practises conformity.

Closed minds can’t preserve an open society. We are proud that Standpoint has upheld the true toleration symbolised by the free press, as the historian Niall Ferguson acknowledges: “In the era of fake news, Standpoint provides authentic comment,” Professor Ferguson tells us. “A single hour of leafing through its pages is worth a year on Twitter.”

Yet even those who benefit most from toleration are unclear about its limits. Bari Weiss, a young New York Times editor, writes about “the Intellectual Dark Web” — a sinister-sounding coterie that apparently includes Jordan Peterson, Ayaan Hirsi Ali and our own Douglas Murray, although this is doubtless news to them. Ms Weiss wants “the institutional gatekeepers to crack the gates open much more”. Does she not realise that she is one of those gatekeepers? “I don’t, however, want to live in a culture where there are no gatekeepers at all,” she complains. This is the voice of a climate of insecurity, where even the civilised are too timid to defend civilisation.

We live in an era of abundance of methods of communication and sources of information. Two centuries ago, at the outset of the modern era, extending the boundaries of discourse was incomparably harder. The obverse of such limitations was the incentive to acquire vast erudition and to travel to the ends of the earth in pursuit of first-hand knowledge. The age in which Western civilisation became conscious of itself was also the age of the genius, the polymath and the explorer. How strange that, of all the European sages of the early 19th century, the one who has been most fêted by the European Union should be Karl Marx, whose spectre has haunted humanity ever since.

In the Berlin of the 1820s, a far greater man, Alexander von Humboldt, was one of the first (along with the Royal Institution) to use the public lecture to astound not only the republic of letters but the newly-educated middle class with his descriptions and discoveries. As Marin Meinhardt shows in A Longing for Wide and Unknown Things (Hurst, £25), her brilliant new biography, Humboldt was an entertainer as well as an educator, deploying all the rhetoric of romanticism to evoke the sublime vistas of the Americas, illuminated by the novelties of science. Kosmos, Humboldt’s unfinished magnum opus, sought to encompass the entire corpus of natural science to depict the earth and its place in the universe. Was this a Romantic or an Enlightenment project? Either way, Humboldt was perhaps the last man who knew everything — and knew how to explain it all, too. The late Stephen Hawking, who enjoyed a similar celebrity in our day, could not even make up his mind about his own subject, cosmology, let alone render it comprehensible. The age of the polymath is well and truly over.